You’ll need to get a new one. I’ve done this before and you can buy 3M adhesive pads at places like Target in the US for around $8. If they’re too big, use scissors to cut them to size and they work just as well, if not better in some cases.
Also, isopropyl alcohol works very well at removing bits of the old adhesive that get left behind. I buy the 91% which works very well.